Numerous methods are disclosed for the preparation of 1,1,1,3,3-pentafluoropropane (CF3CH2CF2H, HFC-245fa). These methods vary widely, due in part to the different starting materials and reaction conditions involved.
HFC-245fa is a known chemical species that has found use as a foam blowing agent and also as a refrigerant. HFC-245fa has been prepared according to one known process via the treatment of 1-chloro-3,3,3-trifluoropropene (CHCl═CHCF3, HCFC-1233zd) with excess HF. However, purification of HFC-245fa from the resulting reaction mixture is difficult because HFC-245fa, HCFC-1233zd and HF are difficult to separate by distillation.
U.S. Pat. No. 6,018,084 to Nakada et al., discloses a process wherein 1,1,1,3,3-pentachloropropane (CCl3CH2CHCl2) is reacted with HF in the gaseous phase in the presence of a fluorination catalyst to form HCFC-1233zd, which is then reacted with HF in the gaseous phase to produce (HFC-245fa).
U.S. Pat. No. 5,895,825 to Elsheikh et al., discloses a process wherein HCFC-1233zd is reacted with HF to form 1,3,3,3-tetrafluoropropene (CF3CH═CHF) followed by further HF addition to form HFC-245fa.
Although the above described methods serve to produce HFC-245fa, these preparations are characterized by numerous disadvantages, including expensive raw materials, poor yields and poor selectivity which preclude their use on a commercial scale.